That's the assessment of the American Society of Civil Engineers, which released its 2017 "infrastructure report card" Thursday, giving the nation's overall infrastructure a grade of D+.

The report came a day after President Donald Trump held a high-profile meeting with a group of executives to discuss his campaign pledge to invest a trillion dollars to upgrade the nation's critical infrastructure, such as highways, bridges, airports and dams.

Details of any spending plan have yet to be released, and it remains to be seen how the Trump administration will pay for the proposed spending.

His spending target, moreover, represents less than a quarter of what's needed to bring the condition of U.S. infrastructure up to a level that would earn it a B grade, according to ASCE estimates.

To reach a comprehensive grade, the association said it evaluated 16 categories of infrastructure, ranging from rail to schools to airports to dams. Its committee consists of civil engineers from across the country who assessed categories such as capacity, condition, funding and public safety, to assign grades across the 16 segments.

Since 1998, grades have been near failing and averaging only Ds, due to "delayed maintenance" and "under investment across most categories," the engineers said.

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Construction crews work on a freeway overpass along Highway 101 in Novato, California.

In addition to assigning grades to America's ports and parks, the 2017 report card projected a total investment of $4.59 trillion that would be required to bring U.S. infrastructure from where it stands today — at a D+ — to a B grade.

"We need our elected leaders ... to follow through on those promises with investment and innovative solutions that will ensure our infrastructure is built for the future," ASCE President Norma Jean Mattei said in a statement.

To close what the association has calculated to be a $2 trillion, 10-year infrastructure investment gap, the nation needs to up investments from all levels of government and the private sector from 2.5 percent to 3.5 percent of Gross Domestic Product by 2025, the report said.

"Infrastructure owners and operators must charge, and Americans must be willing to pay, rates and fees that reflect the true cost of using, maintaining, and improving infrastructure," the group said.

Awaiting Trump's infrastructure plan

With a Trump administration in the White House now, advocacy groups are keeping a close watch on the Republicans' agenda to see how they move forward on infrastructure spending.

"While Congress and states have made some effort to improve infrastructure, it's not enough," Greg DiLoreto, a past ASCE president, said in a statement. DiLoreto said a bill is "overdue" and is costing each American roughly $3,400 per year in disposal income.

In his first speech to a joint session of Congress, Trumplast week proposed $1 trillion in infrastructure investment, "financed through both public and private capital."

That investment, he said, would create "millions of new jobs."

Though infrastructure investment was a major theme of his campaign, the issue has largely taken the back seat to Republican efforts to repeal the Affordable Care Act and pass tax reform.

On Wednesday, though, Trump made strides toward announcing a more formal infrastructure plan, meeting with leading members of the private sector, such as SpaceX Chief Executive Elon Musk and Vornado Realty Trust Chief Executive Steve Roth, asking for their perspectives.

Despite Trump's vocal support for ambitious investment, the White House has yet to release substantive details.

Trump has also suggested that private investors play a role in rebuilding infrastructure. But critics of that approach say the number of potentially profitable projects is limited.

"[Private investment] would not deliver many of the most important needed projects for roads and bridges, public transit, schools and public housing," the Center on Budget Policies and Priorities wrote in a report. "Rather than public investment … the Trump plan relies entirely on private projects through which investors would own the projects, get huge federal tax credits equal to a stunning 82 percent of their equity investment, and make profits from the tolls or fees they would charge to consumers."

Source: California Department of Water Resources

A damaged spillway with eroded hillside is seen in an aerial photo taken over the Oroville Dam in Oroville, California, U.S. February 11, 2017.

The group said Trump's "plan" has no way of ensuring that infrastructure projects flow to communities that are currently underserved by investments, and the administration's ideas of funding are based on many "unrealistic assumptions."

"There's a broad recognition that we need to significantly increase infrastructure investment on a range of things," said Michael Leachman, the center's director of state fiscal research. "But how do you most effectively do that? There's some misguided worry about the debt required to fund big infrastructure projects," he said.

Federal vs. state

States are also stepping up to fund the overhaul of infrastructure, much of which they own, even as many struggle to balance their budgets.

"The Federal government has an important role to play, but the vast majority of infrastructure is owned by states and localities," Leachman said.

That state burden has been amplified by a maintenance backlog that can pose a threat to public safety, as was recently highlighted by last month's emergency spill along the Oroville Dam in California.

The event was a wake-up call for many, the first event of this kind in more than half a century. An emergency order forced nearly 190,000 residents to evacuuate their homes.

The average age of the nation's more than 90,000 dams is 56, according to the American Society of Civil Engineers, with over 15,000 classified as "high hazard" in 2016.

"The number of dams identified as unsafe is increasing at a faster rate than those being repaired," the group said in a statement. About 14 percent of dams are owned or regulated by federal agencies, leaving the rest to states and municipalities, according to the group's data.

Whether federal or state owned, dams in particular are getting less attention in the media than "high profile" bridges or airports, said Tim McCarty, risk control manager at Trident Public Risk Solutions.

The news from the ACSE report card wasn't all bad.

Rail infrastructure received the highest rating — a B — this year. Bridges, ports and solid waste all received C+ grades, implying more effort has been made in these segments.